Chart transport

ABSTRACT

A universal strip chart transport mechanism to support and laterally transport a strip chart between a supply roll and a reroll, said strip chart being adapted to be driven by a drive roll and having perforations adjacent opposite edges thereof for snugly receiving drive pins carried at the opposite ends of the drive roll. The supply roll and reroll are each provided with flanges at the opposite ends thereof, the pairs of flanges at adjacent ends of said rolls being biased toward the other ends of their associated rolls, the biasing forces acting on one pair of flanges being greater than the biasing forces acting on the other pair of flanges. Two modes of operation of the transport mechanism are contemplated, one in which the strip chart is referenced to one edge thereof and another in which the strip chart is referenced to the other edge, the perforations adjacent the remote edge of said strip chart, in each case, being laterally elongated. In said one mode of operation of said transport mechanism, a reference position for said chart is established by said one pair of flanges by the use of retaining means to determine the extreme position to which said one pair of flanges is movable by the associated biasing means. In the alternative mode of operation of said transport mechanism, a reference position for said chart is established by said other pair of flanges by employing the said retaining means to said last mentioned pair of flanges in a fixed position. This arrangement tends to minimize the tendency for the drive pins on the drive roll to become disengaged from the perforations in the chart as the result of lateral expansion and contraction of the chart due to variations in moisture content thereof. In each mode of operation the laterally elongated perforations are at the side of the chart that undergoes the greatest movement as the result of changes in moisture content.

Robinson [451 July 23,1974

[ CHART TRANSPORT 75 Inventor: Clayton F. Rob nson, Philadelphia,

Pa. 1 [73] Assignee: Honeywell Inc., Minneapolis, Minn. 22 Filed:Oct.6,1972

[21] Appl; No.: 295,708

[52] US. Cl. 242/67.2, 242/67.3, 242/719 .Primary Examiner-John W. Huckert Assistant Examiner-J. M. ,Jillions Attorney, Agent, or Firm'fArthurH. Swanson; Lockwood Burton; John Shaw Stevenson s71 ABSTRACT Auniversal strip-chart transport mechanism to support and laterallytransport a strip chart between a supply roll and a reroll, said stripchart being adapted to be driven by a drive roll and having perforationsadjacent opposite edges thereof for snugly receiving Umrath 242/673 R Xdrive pins carried atthe opposite ends of the drive roll. The supplyrolland reroll are each provided with flanges at the opposite endsthereof, the pairs of flanges at adjacent ends of said rolls beingbiased toward the other ends of their associated rolls, the biasingforces acting on one pair of flanges being greater than the'biasingforces acting on the other pair of flanges. Two modes of operation ofthe transport mechanism are contemplated, one in which the strip chartis referenced to one edge thereof and another in which the strip chartis referenced to the other edge, the perforations adjacent the remoteedge of said strip chart, in each case, being laterally elongated. insaid one mode of operation of said transport mechanism, a referenceposition for said chart is established by said one pair of flanges bythe use of retaining means to determine the extreme position to whichsaid one pair of flanges is movable by the associated biasing means. Inthe alternative mode of operation of said transport mechanism, areference position for said chart is established by saidother pair offlanges by employing the said retaining means to said last mentionedpair of flanges'in a fixed position. This arrangement tends to minimizethe tendency for the drive pins on the drive roll to become disengagedfrom theperforationsin the chart as the result of lateral expansion andcontraction of the chart due to variations in moisture content thereof.ln each mode of operation the laterally elongated perforations are atthe side of the chart that'undergoes the greatest movement as the resultof changes in moisture content.

' 4 Claims, 2 Drawing Figures CHART TRANSPORT BACKGROUND OF THEINVENTION Chart paper that has been employed in: strip chart recordershave heretofore used a series of aligned, uniformally spaced apart roundholes adjacent its right or left edge to enable it to be engaged anddriven by a drive chart roll sprocket and a series of aligneduniformally spaced apart horizontally elongated slots adjacentitsopposite left or right edge to enable it to be engaged and driven bysprockets formed on an opposite the chart.

PROBLEMS The aforementioned uniform expansion and/or contraction of thechart forces the wall forming the round sprocket holes in the chart toride in an upward direction over and out of contact with the sprocketson the drive chart roll with which these round sprocket holes areassociated and the chart does not return to 1 its driven position whileexpansion of the 'chart paperoccurs. This chart motion will be in anoutward direction against both of the flanges of the feed roll andreroll spools and outward toward the opposite ends of the platen. Whenthe chart paper contracts this chart motion will be in an inwarddirection away from the opposite walls of the chart platen.

When the round sprocket holes in the chart paper are moved out of thedriving contact with the chart drive pins in the drive chart roll in theaforemention manner the conventional electric motor driven gear drivethat is employed to drive this drive chart roll will not be able tocarry out its prescribed function, namely, that 'of transmitting motionto the drive chart roll in order to pull the chart paper from the chartsupply roll so that the chart can be wrapped on the reroll at aprescribed rate.

SUMMARY OF THE INVENTION A chart transport which the position of theflange of the feed roll and the flange of the reroll that is adjacentthe side of the chart that contains the round holes employed to drivethis drive chart roll will therefore be able to drive the chart atapredetermined'rate of speed while adverse moisture content changes inthe expansion of the chart occurs.

. A better understanding of the present invention may be had when thefollowing detailed description is read in connection with theaccompanying drawings in which: g

FIG. 1 is a partial sectional view taken through the back of anindustrial type chart transport showing a platen having unique supportsfor mounting'the-ends of a feed roll and reroll chart roll thereon thatprevent the sprocket chart drive pins on'an associated drive chart rollfrom becoming disengaged with the round'holes on a chart when a changein the moisture content of the chart occursand FIG. 2 shows how certainparts of the unique'chart roll support construction shown in FIG. 1 canbe relocated to accommodate a labortory type of chart roll that has itsround holes on the opposite side of the chart from that shown-in FIG. 1.

The chart transport 10 is comprised of a U-shaped platen 12 that has arear plate 14, and two side plates The side plate 18 supportsaconventional stub shaft 20 on which a motor drive gear 22 is mounted forrotation. The motor and any desired gear reduction train associatedtherewith is engaged by a motor driven gear of a recorder, not shown, onwhich the subject chart transport 10 is mounted. 1

The gear 22 in turn is shown in driving contact with a second gear 24that is fixably connected to a unitary chart driving shaft 26 that inturn is connected for rotation with a driving chart roll 28.

The shaft 26 is supported in a longitudinal fixed position and forrotation in molded bearings 30, 32 formed in the left and right ends ofthe previously mentioned side plates l6, l8. g

A knurled knob 34 is formed on a left end portion of the driving chartroll 28 for manual rotation of same. A pulley 36 is vfixably mounted toa right end shaft 26 so that it is rotatable therewith.

A second pulley 38 is mounted on the end of a pin shaft 40 which shaftin turn is provided with a'key 42 mounted in a fixed position on itsleft end by means of a threaded screw connector 44..The upper end ofthis connector 44 is bent and is shown fitted into a key slot 46 formedin a tube shaped reroll spool 48. A knurled knob 50 is formed on theouter end of the shaft 40 to provide a means of manually rotating theshaft 40, key

42 and the reroll spool 48 that is fixedly attached platen 12 toaccomodate the'mounting of the pin 58 for longitudinal movement thereon.A coil spring 61 is shown mounted on the rivet head type pin 58 which ex-v tends in spring biased engagement between the outer left side portionof the hub 52 and the inner wall of the left side plate 16 of the platenl2.

The peripheral portion of pin 58 is also provided with two spaced-apartring shaped slots 60, 62. The external cotter 64 is shown retained inengagement with the ring shaped slot 62. I

A second flange 66 for the reroll spool 48 is shown in FlGQl which issimilar to -that which is. in the opposite end position to that shownfor the flange 54. The

3 flange has a hub 68 and tured wall portion 70.

The pin shaft 40 on which the flange is mounted is also provided with aring shaped slot 72 which has an external cotter 74 retained thereon.

A spider spring 76 containing a multiplicity of spring an innercylindrical aperfingers e.g. 78, 80, 82 is shown mounted on the pinshaft 40. This spring is mounted so that it extends between the innersurface of the side plate 18 forming the platen 12 and the outer sidesurface of the flange 66.

' It should be noted at this point that since the external cotter 74 islocated in physical contact with and immediately to the right of the hub68'of the flange 66 that this flange 66 cannot be moved to the right ofthe position shown in FIG. 1 when expansion of the roll of chart paper83 being wrapped on a reroll'spool 48 occurs during an'increase inhumidity and in which a related moisture content of the chart paper isincreased.

The fixed flange 66 thus establishes a chart stop plate or referencesurface from which only transverse expansion of the industrial type ofstrip chart 83 in a right to left direction against the flange 54 andagainst the bias of spring 61 can take place. In this way the roundholes, for example, 84, 86, 88 90 on the chart 83 are pre vented frommoving upward over and out of driving contact with the associatedsprocket drive pins 92, 94, 96, 98. Furthermore, in the aforementionedmanner the past practice of the disengagement of apertures in the chartpaper with its associated sprocket drive will be eliminated.

is comprised of a cylindrical spool 100 mounted on a hub portion 102 ofthe flange 104 and on a hub portion 106 of the flange 108. The centralportion of flange 104 has a cylindrical apertured wall 110 that ismounted for sliding laterally-along a pin shaft 112. The pin shaft 112is shown mounted in a fixed position by means of a screw member 114 in amolded bearing member 116 that is formed in the left side plate 16 ofthe platen 12. A coil spring 118 extends between the inside surface ofthe side wall 16 and the hub portion 102 of the flange 104 to maintainthe flange 104 in spring biased engagement with the left end of the rollof chart paper 83 that is wrapped on the spool 100. In this way the leftend of the roll of the chart paper 83 can be expanded in a directionagainst a direction in which the spring 118 is applying its force to theend of the feed roll of the paper 83.

The central portion of the flange 108 has a cylindrical apertured wall120 that is mounted in a fixed posi tion on a pin shaft 122 by means ofa pair of external cotters 124, 126 that are in turn retained in a fixedposition in their associated grooves 128, 130 formed in pin shaft 122.

The rotatable pin shaft 122 .is mounted in molded bearing 132 formed inthe right side plate 18 of the platen l2 and is restrained from lateralmovement by means of the head of a screw member 131 attached thereto.

A spider spring 134 that is similar to the previously mentioned spring76, which has a multiplicity of spring fingers 136, 137, 138, is shownmounted on the pin shaft 122. The spring 134 is mounted at a locationthat extends between the inner surface of the side plate 18 forming theplaten 12 and the outer side surface of the flange 108.

It should'be noted that since the external cotter 128 is located inphysical contact with, and immediately to the right of the hub 106 ofthe flange 108, this flange 108 cannot be moved to the right of theposition shown in FIG. 1 when expansion of the roll of the chart paper83 being pulled off the feed roll 100 occurs during a humidity change inwhich the moisture content of the chart paper 33 is increased.

The fixed flange 108 thus establishes, in a manner similar to thatalready described for the flange 66 of the reroll spool 48, areference'surface from which only transverse expansion of chart 83 in aright to left direction against flange 104 and against the bias ofspring 118 can take place.

Furthermore, in this manner the round holes for example 84, 86, 88, 90on the chart 83 are prevented from moving upward over and out of drivingcontact with their associated drive pins 92, 94, 96, 98. In this way thepast practice of disengagement of round apertures in the chart paper 83with its associated sprocket drive will be eliminated as successiveportions of chart paper 83 are pulled by a drive chart roll 28 off afeed roll 100.

FIG. 1 shows a plate 142 which is attached at one end to a centralportion of the platen 12 and its free end in spring biased contact withthe chart 83 as it is moved between feed roll 100 and drive chart roll28 so that a drag force will be applied to the chart paper 83.

A series of arrows are shown in FIG. 1 to indicate the direction inwhich the chart paper 83 is pulled off of the back side surface of feedroll 100 by the drive chart roll 28, once over the drive chart roll,along the external front vertical surface of the platen 14 toward thelower end of the platen and then wrapped into a roll about thepreviously mentioned reroll driving spool 48.

FIG. 2 shows a laboratory type of chart paper 144 that is of the samewidth as chart paper 83 shown in FIG. 1. FIG. 2 differs from FIG. 1 inthat its chart paper 144 has its driving cylindrical sprocket driveapertures 146, 148, 150, 152 adjacent to a left side of the chart 144 inlieu of being adjacent to right side of chart 83 as shown in FIG. 1.

FIG. 1 shows sprocket drive pins e.g. pins 154, 156, 158, 160 that areequally spaced about and which protrude from the periphery of drivechart roll 28. These pins 154-160 are centrally located and in drivingrelationship with elongated slots e.g. 162; 164; 166; 168; that areformed in spaced apart relationship adjacent to and along the entireleft side of the chart 83.

The sprocket drive pins 92-98 shown in FIG. 2 are located on the rightside of the chart 144 and are shown in driving relationship withelongated slots e.g. 170, 172, 174, 176 that are in spaced apartrelationship adjacent to and along the entire right side of the charttion in FIG. 2. More specifically, the external cotter 74 is removedfrom its FIG. 1 position in which it acts as a stop against left toright movement of the flange 66 and placed into a new FIG. 2 position sothat expansion of chart 144 on spool 48 will be able to force flange 66to the rightof the position upon change in its moisture content.

the-left to right-motion of flange108, when expansion of charts 83 inFIG. 1 occurred, is now used to prevent the flange l0 4'from being movedto .the right of the position-shown by the force of spring 118. Theflange 108 will thus beallowed tomove to the right of its position shownin FIG. .2 when expansion of chart 144 occurs It can be seen that whenthe external cotter 126 is placed in the positionas shown in FIG. 2rotation of the i screw member 114 will selectively allow movement ofthe pin shaft112, thecotter 126 and the flange 104 to a desired fixedposition that of the'position shown. I r

vThe-flange 104'will thus act as a reference line from which expansionof the chart 144 can take place only in a left to right direction and ina manner similar to that previously described under the description ofFIG.

Selective relocation of the external cotters 74 and 2126 between theFIG, .-1,and FIG. 2, positions in the manner just describedwill providea single chart transport and agood uniform holding,'feeding, guiding,driving and rerolling of not only the peripherated type of chart paper83 shown in FIG. 1 but also the other different type of peripheratedchart paper 144 as shown in FIG. 2 when changes in the moisture contentof either of these chart papers occur.

It should be noted that the major problem that the unique charttransport 10 presented herein solved is its ability to preventdisengagement of the sprocket drive pin with the circular drive holes ina strip chart when shown. This chart expansion 1 The embodiments of aninvention in which an exclusive property or privilege is claimed aredefined as follows:

l. A universal strip chart transport mechanismuseful 'for supporting andlongitudinally transporting strip one of said edges are laterallyelongated and in another form being characterized inthat-the saidperforations adjacent the other edge are laterally elongated, therebyallowing lateral expansion or contraction of said charts with changes inthe moisture content thereof while in each case minimizing the tendencyfor the drive pins of is either to the right or left said drive roll tobecome disengaged from the said perforations of said charts, a supplyroll and a reroll between which said chart is adapted to be transported,

said supply roll and reroll having aflange at each of their oppositeends, meansv associatedwith each said flange forbiasing said flanges inan axially inward direction, the force of said biasing means in oneaxial dithe moisture of the chart is increased and regardless of whetherthe type of charts being used has its circular drive holes locatedadjacent its right edge as shown for the industrial type of chart 83 inFIG. 1 or adjacent its left edge as shown for the laboratory type ofchart 144 in FIG. 2. 7

, Since very little shrinkage. in each of the aforementioned charts 83and 144 will occur between the small portion of each of these chartsthat is between the rounded holes and its adjacent edge in the eventthat the moisture content of these charts is lowered there will beverylittle possibility of these rounded holes becoming disengaged fromtheir associated drive sprockrection on one of said flanges of each saidroll being greater than the force on the other of said flanges in theother axial direction, transferable retainer means associated with saidsupply roll and reroll to establish a ref- .erence position for theflanges on which the greater bi asing forces are activeby.determiningthe extreme positions to which said flanges are movableaxially inward by said biasing means, said retainer means beingtransferable to establish a reference position for the other flanges onwhich the weaker biasing forces are active to retain each of said lastmentioned flanges in a fixed position, whereby both forms of stripcharts may be transported by said transport mechanism.

2. A strip chart transport apparatus as defined in claim 1 wherein anadjustable support means is employed to selectively adjust the positionof that supply roll flange to which the stronger biasing force isapplied.

3. Astrip chart transport apparatus as defined in claim 1 wherein theflanges of said supply roll and re roll spools are each provided withhub portions that are rotatably supported on the outer surface of aseparate stationary pin shaft support member. 7

4. A strip chart transport apparatus as defined in claim 1 wherein theflanges of said supply roll and reroll are each provided with a hubportion that is rotatably supported onan individually associatedstationary pin shaft support member and wherein said transferableretainer means is an external cotter.

1. A universal strip chart transport mechanism useful for supporting and longitudinally transporting strip charts having perforations adjacent opposite edges thereof for snugly receiving drive pins carried at the opposite edges of a drive roll, said strip charts in one form being characterized in that the perforations adjacent one of said edges are laterally elongated and in another form being characterized in that the said perforations adjacent the other edge are laterally elongated, thereby allowing lateral expansion or contraction of said charts with changes in the moisture content thereof while in each case minimizing the tendency for the drive pins of said drive roll to become disengaged from the said perforations of said charts, a supply roll and a reroll between which said chart is adapted to be transported, said supply roll and reroll having a flange at each of their opposite ends, means associated with each said flange for biasing said flanges in an axially inward direction, the force of said biasing means in one axial direction on one of said flanges of each said roll being greater than the force on the other of said flanges in the other axial direction, transferable retainer means associated with said supply roll and reroll to establish a reference position for the flanges on which the greater biasing forces are actIve by determining the extreme positions to which said flanges are movable axially inward by said biasing means, said retainer means being transferable to establish a reference position for the other flanges on which the weaker biasing forces are active to retain each of said last mentioned flanges in a fixed position, whereby both forms of strip charts may be transported by said transport mechanism.
 2. A strip chart transport apparatus as defined in claim 1 wherein an adjustable support means is employed to selectively adjust the position of that supply roll flange to which the stronger biasing force is applied.
 3. A strip chart transport apparatus as defined in claim 1 wherein the flanges of said supply roll and reroll spools are each provided with hub portions that are rotatably supported on the outer surface of a separate stationary pin shaft support member.
 4. A strip chart transport apparatus as defined in claim 1 wherein the flanges of said supply roll and reroll are each provided with a hub portion that is rotatably supported on an individually associated stationary pin shaft support member and wherein said transferable retainer means is an external cotter. 